Abstract
Background:
Little is known about the forces carried by the Taylor Spatial Frame (TSF) hexapod fixator. Our aim was to measure the TSF resultant force and how this changed during the consolidation phase.
Method:
Five patients undergoing correction of tibial deformities were recruited. Measurements were taken at 2, 4, 8 and 12 weeks post-correction during various activities. Instrumented struts incorporating strain gauges measuring axial force were temporarily used each time. Strut forces and lengths were used to determine frame kinetics. The resultant axial fixator forces and moments were calculated relative to sitting. Ground reaction forces (GRF) were measured using the treadmill force plates.
Results & Discussion:
Due to the subjects' varying confidence in weight bearing the forces varied both inter- and intra-activity and over post-corrective time. Variation in individual strut forces produced a resultant force and bending moment across the fixation. As the healing bone assumed more load over time there was a reduction in the force and bending excursions across the frame as a percentage of GRF, achieving a minimum by 8 weeks.
Conclusion:
Instrumented TSFs are a useful means of assessing the forces acting during healing. Monitoring of these forces can determine optimal removal.
